Simultaneous multi-slice (SMS) acquisition enhances the sensitivity of hemodynamic mapping using gas challenges

Area of Science:

• Neuroimaging
• Cardiovascular Sciences
• Medical Physics

Background:

• Gas inhalation techniques, such as CO2 and O2, are used for hemodynamic mapping (cerebrovascular reactivity and cerebral blood volume) in MRI.
• These methods offer advantages like avoiding gadolinium contrast agents and assessing vascular reserve.
• However, poor sensitivity and reliability limit their clinical utility.

Purpose of the Study:

• To investigate the impact of simultaneous multi-slice echo planar imaging (SMS EPI) on the sensitivity of gas inhalation MRI.
• To compare the sensitivity of SMS EPI (SMS factor 2 and 3) with conventional EPI (SMS factor 1) for CO2 and O2 inhalation studies.
• To assess the potential for reducing scan duration while maintaining sensitivity.

Main Methods:

• Comparison of CO2 and O2 inhalation MRI data acquired using conventional EPI (SMS1) and SMS EPI (SMS2, SMS3).
• Sensitivity analysis performed on voxel-wise data across the brain.
• Statistical comparison of sensitivity between SMS and conventional EPI methods.

Main Results:

• SMS EPI demonstrated significantly higher sensitivity compared to conventional EPI (p=0.01).
• No significant difference in sensitivity was observed between SMS2 and SMS3 (p=0.3).
• Approximately 20-30% of brain voxels showed significant sensitivity enhancement with SMS, with others showing non-significant increases.

Conclusions:

• SMS EPI significantly enhances the sensitivity of gas inhalation MRI for hemodynamic mapping.
• SMS EPI allows for reduced scan times by up to 50% while preserving sensitivity.
• This improved sensitivity and efficiency can advance the clinical application of gas inhalation MRI.